Unconsolidated surficial deposits, undivided

Unit symbol: Qs
Age range Quaternary (1.806 to 0 Ma)
Lithology: Unconsolidated
Group name: Unconsolidated and poorly consolidated surficial deposits
Unconsolidated, poorly to well-sorted, poorly to moderately well-stratified deposits; consist predominantly of alluvial, colluvial, marine, lacustrine, eolian, and swamp deposits. May include some glacial deposits. Also includes widespread glacial and periglacial deposits that consist of end, lateral, and ground moraine, outwash, rock glacier deposits, and other glacial and periglacial deposits as well as glacially scoured bedrock that may be covered with thin, glacially derived deposits. These glacial deposits are of Holocene and Pleistocene age and may include small areas of potentially latest Tertiary deposits. Map unit locally includes reworked volcanic debris as well as block and ash flows. On generalized map, shown as part of unit QTs

Source map information

Source map Wilson, F.H., Detterman, R.L., Miller, J.W., and Case, J.E., 1995, Geologic map of the Port Moller, Stepovak Bay, and Simeonof Island quadrangles, Alaska: U.S. Geological Survey Miscellaneous Investigation Map I-2272, 2 sheets, scale 1:250,000.
Symbol Qaf
Unit name Alluvial fan and landslide deposits
Description Locally mapped; grain size in this unit ranges from coarse, subangular rock fragments to fine sand and silt. Alluvial fans either typically have a well-developed cone shape, or multiple cones coalescing into aprons. Landslide deposits have poorly developed to well-developed lobate morphology
Lithology Unconsolidated

Correlated geologic units

Label Qaf
Description Alluvial fan and talus deposits
Geologic age Pleistocene to Holocene
Geologic setting Unconsolidated
Lithology Form Importance
Gravel < Coarse-detrital < Unconsolidated Colluvial Major
Boulders < Coarse-detrital < Unconsolidated Colluvial Minor
Sand < Coarse-detrital < Unconsolidated Colluvial Minor
Silt < Fine-detrital < Unconsolidated Colluvial Minor